Publications

Although the Gila Monster (Heloderma suspectum) is widely distributed throughout the Sonoran and portions of the Mojave Deserts of the southwestern United States and northwestern Mexico, details of its distribution in California are imperfectly known, due to the apparent rarity of the species in that state. In their review of Gila Monster records for California, Lovich and Beaman (2007)...

Desert dust, both modern and ancient, is a critical component of the Earth system. Atmospheric dust has important effects on climate by changing the atmospheric radiation budget, while deposited dust influences biogeochemical cycles in the oceans and on land. Dust deposited on snow and ice decreases its albedo, allowing more light to be trapped at the surface, thus increasing the rate of...

The future distribution of the Joshua tree (Yucca brevifolia) is projected by combining a geostatistical analysis of 20th-century climates over its current range, future modeled climates, and paleoecological data showing its response to a past similar climate change. As climate rapidly warmed ;11 700 years ago, the range of Joshua tree contracted, leaving only the populations near what...

Global temperature increases and precipitation changes are both expected to alter ecosystem carbon (C) cycling. We tested responses of ecosystem C cycling to simulated climate change using field manipulations of temperature and precipitation across a range of grass-dominated ecosystems along an elevation gradient in northern Arizona. In 2002, we transplanted intact plant–soil mesocosms...

Accurately predicting the effects of global change on net carbon (C) exchange between terrestrial ecosystems and the atmosphere requires a more complete understanding of how nutrient availability regulates both plant growth and heterotrophic soil respiration. Models of soil development suggest that the nature of nutrient limitation changes over the course of ecosystem development...

Since the 1980s wildlife managers in the United States and Canada have expressed increasing concern about the physical threat posed by cougars (Puma concolor) to humans. We developed a conceptual framework and analyzed 386 human– cougar encounters (29 fatal attacks, 171 instances of nonfatal contact, and 186 close-threatening encounters) to provide information relevant to public safety...

In the deserts of the southwestern U.S., burrows are utilized by the Desert Tortoise to escape environmental extremes (reviewed by Ernst and Lovich 2009. Turtles of the United States and Canada. 2nd ed. Johns Hopkins Univ. Press, Baltimore, Maryland. 827 pp.). However, the potential for mortality through burrow collapse and entrapment is poorly documented. Nicholson and Humphreys (1981

The article reviews graphical interpretation of the four monitoring methods that can be used to generate a variety of indicators of rangeland ecosystem function. Data for all four of the monitoring methods can be recorded on a single data sheet that is designed to be usable by somebody with minimal literacy. Indicators of plant and ground cover are central to most long-term monitoring...

Estimating phosphorus (P) availability is difficult—particularly in infertile soils such as those exposed after glacial recession—because standard P extraction methods may not mimic biological acquisition pathways. We developed an approach, based on microbial CO2 production kinetics and conserved carbon:phosphorus (C:P) ratios, to estimate the amount of P available for microbial growth...

I observed an adult Desert Tortoise and an adult Red Diamond Rattlesnake (sexes unknown) in a shallow tortoise burrow on 6 January 1997 at a wind energy generation facility near Palm Springs, Riverside Co., California, USA (33.9599°N, 116.6613°W).

Documenting how different regions across a species' breeding and nonbreeding range are linked via migratory movements is the first step in understanding how events in one region can influence events in others and is critical to identifying conservation threats throughout a migratory animal's annual cycle. We combined two studies that evaluated migratory connectivity in the Willow...

Ecosystems can shift between alternative states characterized by persistent differences in structure, function, and capacity to provide ecosystem services valued by society. We examined empirical evidence for alternative states in a semiarid grassland ecosystem where topographic complexity and contrasting management regimes have led to spatial variations in levels of livestock grazing...